Unless you're going to start breeding with the intention of keeping hundreds of fry to maturity, please don't use a birthing trap. It's extremely stressful to the pregnant fish, to the point that she'll self abort the fry or reabsorb them. The reason they have so many fry is with the anticipation that most will NOT survive, so they have a lot knowing that at least a few will. The moss is great for fry, and if they're smart (which apparently some are) they'll hide there.
I was not going to breed my platties, they seem to have that all under control by themselves. Didn't like the trap the one time I put her in it, she seemed too confined. The reason for trying the trap was so that my kids could see the fry, but hey they found them fine enough swimming free (and for their lives from the other fish).
Fry question? Since I am not trying to breed them, but inevitably a couple could survive, and I do not want to dissuade their survival, what do I feed them?? I usually give my fish flake that I break up a bit (mid size pieces). I don't see the fry getting to eat them and if I crush up flake really small, my filter and flow in the tank will probably blow the crushed pieces away from where the fry are hiding (I placed the moss mound as far from the filter inlet as possible, so they would not be accidentally sucked up the filter when they are just trying to hide).
Another question, at what age (week) will the fry be big enough to survive on their own in the tank w/o having to hide all day/night?
We did call her Vicky Pollard though 
